Maybe this will help
Say the temperature is 13 degrees and then there is a really cold snap and the temperature falls by 25 degrees. what will be the new temperature?
If the answer is not obvious, draw a number line and pretend it is a thermometer.
Start at 13 then take away 1, then another 1, ...... until you have taken away 25. What number did you get to?
Does this help you? What answer did you get?
+118654 
